Deconvolution of high-resolution spectra as a signal-to-noise ratio enhancement method     

J. R. Barnes 《Monthly notices of the Royal Astronomical Society》2004,348(4):1295-1300

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A quasi-geostrophic diagnosis of the zonal flow associated with cut-off lows over South Africa and surrounding oceans     

Ndarana  Thando  Rammopo  Tsholanang S.  Chikoore  Hector  Barnes  Michael A.  Bopape  Mary-Jane 《Climate Dynamics》2020,55(9-10):2631-2644

Climate Dynamics - The zonal flow associated with cut-off lows (COLs) comprises two jet streaks of different spatial extents. The smaller scale jet streak, located north of the COLs, forms as a...  相似文献   

Behaviour of the winter North Atlantic eddy-driven jet stream in the CMIP3 integrations   总被引：1，自引：1，他引：0  

Abdel Hannachi  Elizabeth A. Barnes  Tim Woollings 《Climate Dynamics》2013,41(3-4):995-1007

A systematic analysis of the winter North Atlantic eddy-driven jet stream latitude and wind speed from 52 model integrations, taken from the coupled model intercomparison project phase 3, is carried out and compared to results obtained from the ERA-40 reanalyses. We consider here a control simulation, twentieth century simulation, and two time periods (2046–2065 and 2081–2100) from a twenty-first century, high-emission A2 forced simulation. The jet wind speed seasonality is found to be similar between the twentieth century simulations and the ERA-40 reanalyses and also between the control and forced simulations although nearly half of the models overestimate the amplitude of the seasonal cycle. A systematic equatorward bias of the models jet latitude seasonality, by up to 7°, is observed, and models additionally overestimate the seasonal cycle of jet latitude about the mean, with the majority of the models showing equatorward and poleward biases during the cold and warm seasons respectively. A main finding of this work is that no GCM under any forcing scenario considered here is able to simulate the trimodal behaviour of the observed jet latitude distribution. The models suffer from serious problems in the structure of jet variability, rather than just quantitiative errors in the statistical moments.  相似文献   

The Helioseismic and Magnetic Imager (HMI) Vector Magnetic Field Pipeline: Overview and Performance     

J. Todd Hoeksema  Yang Liu  Keiji Hayashi  Xudong Sun  Jesper Schou  Sebastien Couvidat  Aimee Norton  Monica Bobra  Rebecca Centeno  K. D. Leka  Graham Barnes  Michael Turmon 《Solar physics》2014,289(9):3483-3530

The Helioseismic and Magnetic Imager (HMI) began near-continuous full-disk solar measurements on 1 May 2010 from the Solar Dynamics Observatory (SDO). An automated processing pipeline keeps pace with observations to produce observable quantities, including the photospheric vector magnetic field, from sequences of filtergrams. The basic vector-field frame list cadence is 135 seconds, but to reduce noise the filtergrams are combined to derive data products every 720 seconds. The primary 720 s observables were released in mid-2010, including Stokes polarization parameters measured at six wavelengths, as well as intensity, Doppler velocity, and the line-of-sight magnetic field. More advanced products, including the full vector magnetic field, are now available. Automatically identified HMI Active Region Patches (HARPs) track the location and shape of magnetic regions throughout their lifetime. The vector field is computed using the Very Fast Inversion of the Stokes Vector (VFISV) code optimized for the HMI pipeline; the remaining 180^° azimuth ambiguity is resolved with the Minimum Energy (ME0) code. The Milne–Eddington inversion is performed on all full-disk HMI observations. The disambiguation, until recently run only on HARP regions, is now implemented for the full disk. Vector and scalar quantities in the patches are used to derive active region indices potentially useful for forecasting; the data maps and indices are collected in the SHARP data series, hmi.sharp_720s. Definitive SHARP processing is completed only after the region rotates off the visible disk; quick-look products are produced in near real time. Patches are provided in both CCD and heliographic coordinates. HMI provides continuous coverage of the vector field, but has modest spatial, spectral, and temporal resolution. Coupled with limitations of the analysis and interpretation techniques, effects of the orbital velocity, and instrument performance, the resulting measurements have a certain dynamic range and sensitivity and are subject to systematic errors and uncertainties that are characterized in this report.  相似文献   

A CH₃CN and HCO⁺ survey towards southern methanol masers associated with star formation     

C. R. Purcell  R. Balasubramanyam  M. G. Burton  A. J. Walsh  V. Minier  M. R. Hunt-Cunningham  L. L. Kedziora-Chudczer  S. N. Longmore  T. Hill  I. Bains  P. J. Barnes  A. L. Busfield  P. Calisse  N. H. M. Crighton  S. J. Curran  T. M. Davis  J. T. Dempsey  G. Derragopian  B. Fulton  M. G. Hidas  M. G. Hoare  J.-K. Lee  E. F. Ladd  S. L. Lumsden  T. J. T. Moore  M. T. Murphy  R. D. Oudmaijer  M. B. Pracy  J. Rathborne  S. Robertson  A. S. B. Schultz  J. Shobbrook  P. A. Sparks  J. Storey  T. Travouillion 《Monthly notices of the Royal Astronomical Society》2006,367(2):553-576

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A wide-field H i study of the NGC 1566 group     

Virginia A. Kilborn  Bärbel S. Koribalski  Duncan A. Forbes  David G. Barnes  Ruth C. Musgrave 《Monthly notices of the Royal Astronomical Society》2005,356(1):77-88

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Lagrangian measurements and modelling of fluid advection in the inner surf and swash zones     

T.E. Baldock  A. KudoP.A. Guard  J.M. AlsinaM.P. Barnes 《Coastal Engineering》2008

New laboratory and field data are presented on fluid advection into the swash zone. The data illustrate the region of the inner surf zone from which sediment can be directly advected into the swash zone during a single uprush, which is termed the advection length. Experiments were conducted by particle tracking in a Lagrangian reference frame, and were performed for monochromatic breaking waves, solitary bores, non-breaking solitary waves and field conditions. The advection length is normalised by the run-up length to give an advection ratio, A, and different advection ratios are identified on the basis of the experimental data. The data show that fluid enters the swash zone from a region of the inner surf zone that can extend a distance seaward of the bore collapse location that is approximately equal to half of the run-up length. This region is about eight times wider than the region predicted by the classical swash solution of Shen and Meyer [Shen, M.C., Meyer, R.E., 1963. Climb of a bore on a beach. Part 3. Runup. Journal of Fluid Mechanics 16, 113–125], as illustrated by Pritchard and Hogg [Pritchard, D., Hogg, A.J., 2005. On the transport of suspended sediment by a swash event on a plane beach. Coastal Engineering 52, 1–23]. Measured advection ratios for periodic waves show no significant trend with Iribarren number, consistent with self-similarity in typical swash flows. The data are compared to recent characteristic solutions of the non-linear shallow water wave (NLSW) equations and both finite difference and finite volume solutions of the NLSW equations.  相似文献   

Limits on the 2.2-μm contrast ratio of the close-orbiting planet HD 189733b     

J. R. Barnes  Travis S. Barman  L. Prato  D. Segransan  H. R. A. Jones  C. J. Leigh  A. Collier Cameron  D. J. Pinfield 《Monthly notices of the Royal Astronomical Society》2007,382(1):473-480

We obtained 238 spectra of the close-orbiting extrasolar giant planet HD 189733b with resolution   R ∼ 15 000  during one night of observations with the Near-Infrared High-Resolution Spectrograph (NIRSPEC), at the Keck II Telescope. We have searched for planetary absorption signatures in the  2.0–2.4 μm  region where H₂O and CO are expected to be the dominant atmospheric opacities. We employ a phase-dependent orbital model and tomographic techniques to search for the planetary absorption signatures in the combined stellar and planetary spectra. Because potential absorption signatures are hidden in the noise of each single exposure, we use a model list of lines to apply a spectral deconvolution. The resulting mean profile possesses a signal-to-noise ratio (S/N) that is 20 times greater than that found in individual lines. Our spectral time series thus yields spectral signatures with a mean S/N = 2720. We are unable to detect a planetary signature at a contrast ratio of  log₁₀( F _p/ F _*) =−3.40  , with 63.8 per cent confidence. Our findings are not consistent with model predictions which nevertheless give a good fit to mid-infrared observations of HD 189733b. The 1σ result is a factor of 1.7 times less than the predicted 2.185-μm planet/star flux ratio of  log₁₀( F _p/ F _*) ∼−3.16  .  相似文献   

Estuaries and nutrients: Bruce J. Neilson and L. Eugene Cronin (Editors), Humana Press,Clifton, NJ,U.S.A., 1981 (distr. by John Wiley,Chichester). x + 643 pp. US $ 64.50 (U.S.A.)/US $ 74.50 (outside U.S.A.) (£43.50). Hardback     

M. Barnes 《Marine Chemistry》1983,13(4):358

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Comment on the paper ‘solution of one-fluid model equations with short range retarding magnetic forces for the quiet solar wind’ by Cuperman and Harten     

Aaron Barnes 《Astrophysics and Space Science》1976,40(1):35-38

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